Why does the AWGN reference design use 8 BlockRAM (BRAM) instead of 4 BlockRAM?
The design should use only 4 BRAM, but it actually uses 8. The problem is due to the fact that 4 of the ROM should be using Distributed Memory.
To work around the problem, you should change the Implementation parameters to "use distributed memory" for the following 4 ROM. Change all of the ROM blocks in the Box_Muller.
You can then save this back into the library by breaking the link and then restoring it.
1. Place the AWGN block in your design.
2. Right-click the block and select Link Options -> Disable Link.
3. Right-click the block and select Look Under Mask.
4. Use the Model Browser to Select the White Gaussian Noise Generator/Box-Muller1.
5. Right-click the block and select Link Options -> Disable Link.
6. Select the F block.
7. Double-click ROM5.
8. Check the Implementations Parameter checkbox.
9. Check the Use Distributed Ram checkbox.
10. Click OK.
Repeat Steps 4 through 10 for Box-Muller2, Box-Muller3, and Box-Muller4. The only difference is that you will need to Select Block F1 and ROM6.
Once you have finished making these changes, you can restore the link and save the changes to your library.
1. Return to AWGN block.
2. Right-click it and select Link Option -> Restore Link.
3. Select Update Library from the pop-up box that appears.
This has been fixed in System Generator for DSP 8.1.